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Fluorescent Phytoplankton
Thanks to NASA's Aqua satellite, scientists are now learning more about the phytoplankton that are vital to so many ecosystems around the world. "In fact," according to NASA, "phytoplankton account for half of all photosynthetic activity on Earth." Previously, scientists were only able to observe green chlorophyll, indicating the amount of phytoplankton present in the ocean. Now, with the help of the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the Aqua satellite, they can study how well the phytoplankton are functioning based on their fluorescence. Scientists have never had the capability to observe fluorescence at the global level until the Aqua satellite.
Phytoplankton are microscopic plants that use the sun's light to create the energy they need to make food, a process called photosynthesis. Much of any extra energy is released as heat, but a small portion is also emitted as fluorescent light, which is red in wavelength. The amount of light that is emitted from the plants indicates their condition.
Specifically, scientists are looking at how varying levels of iron affect the phytoplankton. When the microscopic plants do not receive enough iron to perform photosynthesis, they produce more fluorescence. The iron in the water is deposited by winds carrying dust from the deserts; thus, phytoplanktons' fluorescence sheds light on environmental changes and trends.
For example, during the monsoon season in the Indian Ocean, fluorescence levels are high because the amount of iron in the winds is limited. Since much of the world's oceans remain unexplored, the Aqua satellite is helpful in allowing researchers to see how phytoplankton are responding to global changes.
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